The present invention relates to thread stands for holding thread reels or spools, each having an upper thread wound thereon, vertically upright at predetermined positions on a thread stand plate, and more particularly to thread stands for use in embroidery sewing machines and various types of industrial sewing machines.
In not only embroidery sewing machines but also industrial sewing machines, requiring upper threads, a thread stand plate 5 is provided, over a machine head, for vertically supporting a plurality of thread spools 51 each having an upper thread wound thereon as illustrated in FIG. 7. FIG. 7 shows a typical example of a conventionally-known thread stand, where the thread stand plate 5 has a plurality of spool pins 52 disposed vertically thereon as members for holding the thread spools 51 substantially upright at predetermined positions. As illustratively seen in FIG. 8, an umbrella member 53 for preventing undesired shaking movement of the thread spool 51 is fitted over the each of the spool pins 52. More specifically, with four resilient vanes of the umbrella member 53, a cone (i.e., conical winding core) 51a of the thread spool 51 is held against undesired shaking movement relative to the spool pin 52. Portion of the thread paid out from the thread spool 51 is first directed to an upper thread course and then directed to be supplied to a machine head. If, during that time, a slack occurs in the thread wound in the thread spool 51, the thread may sag from the outer periphery of the spool 51 so that it may get caught by a lower peripheral edge of the thread spool 51 when the upper thread is pulled up in such a sagging state. To avoid the inconvenience, the conventionally-known thread stand has a doughnut-shaped supporting ring 54, formed of felt or the like, provided on the thread stand plate 5 to fit on the spool pin 52, and the thread spool 51 is placed on such a supporting ring 54. With a lower end portion of the cone 51a of the thread spool 51 inserted in a central hole of the supporting ring 54 and a lower end surface 51b of the thread spool 51 placed in close contact with the upper surface of the supporting ring 54, as shown in FIG. 8, it is possible to prevent the thread from undesired sagging.
Heretofore, screwing has been employed most commonly as a way of fixing the spool pin 52 substantially upright on the thread stand plate 5. However, with sewing machines having a great many thread spools to be supported substantially upright, such as industrial multiH-head embroidery sewing machines, screwing the extremely the extremely many spool pins 52 would require great amounts of time and labor and hence high cost. In view of this, Japanese Patent Application Laid-open Publication No. HEI-5-272047 (hereinafter referred to as Patent Literature 1) discloses forming each spool pin of synthetic resin and resiliently fitting a base portion (lower end portion) of the spool pin into a mounting hole of the thread stand plate to thereby vertically fixing the spool pin to the thread stand. Further, Japanese Patent Application Laid-open Publication No. HEI-9-239172 (hereinafter referred to as Patent Literature 2) discloses mounting a bush 55 of synthetic resin in a mounting hole of the thread stand plate 5 and fitting a base portion (lower end portion) of the spool pin into the bush 55 so that the spool pin 52 can be firmly retained in place while resiliently deforming the bush 55 outwardly, as illustrated in FIG. 8.
The constructions disclosed in Patent Literature 1 and Patent Literature 2 identified above facilitate attachment of the spool pin to the thread stand plate, because they can vertically fix the spool pin to the thread stand plate by just inserting the spool pin into the stand plate without using screwing. However, with the construction disclosed in Patent Literature 1, where the spool pin is fitted directly into the thread stand plate and the thread spool is supported only by the spool pin and thread stand plate, mounting stability of the thread spool tends to be insufficient if the inner open space of the winding core is greater than the thickness of the spool pin. Similarly, with the construction disclosed in Patent Literature 2, where the bush 55 only supports and retains the spool pin thereon, mounting stability of the thread spool tends to be insufficient if the inner space of the winding core is greater than the thickness of the spool pin. Thus, in some of the cases where the winding core is in the form of a cone having a relatively great inner open space as in the thread spool 51 of FIG. 8, an umbrella member 53 is fitted over the spool pins 52 and a supporting ring 54 is provided on the thread stand, to enhance the mounting stability.
Recently, some new or special types of thread spools have been on the market. Such a special type of thread spool can not be vertically fixed to the thread stand with only the conventional spool pin (or combination of the spool pin and umbrella member) of the sewing machine, and a special connection member matching the special type of thread spool is required. Such a special connection member, which is supplied to each user by the same manufacturer as the special type of thread spool, is fitted on the spool pin positioned substantially upright in advance on the thread stamp plate. However, because it is necessary to use a dedicated connection member for each individual special type of thread spool and thus change the type of connection member to be used per change in the type of thread spool to be set on the sewing machine, which would involve very cumbersome operation.